Like most smokers, my lungs cleared up when I started vaping and have stayed that way for 6 months... night-time wheezing stopped completely, allergy symptoms decreased, etc, and it happened fast (one week) but, six months in, the last few days my old chest congestion and drippy nose are back but not to the point of wheezing. I don't know if its because allergy season is here or its an offending flavoring I used for the first time a few days ago. Time will tell but I do wish peeps experiencing congestion would say what flavors/brands and PGVG they're using or if they changed their PG/VG content when the problems started. IE: I'm trying to say, I don't think the problems are with vaping but with what's being vaped. Its not just flavorings either. I also suspect, but can't find anything about it, that there are differences in VG. One vendor-purchased VG causes congestion and another doesn't at the same PG/VG ratios. I have tried different PGs in the unflavored mixes to check it out and its definitely the type of VG causing it.
Edit: well, crap... I didn't do what I was asking for (duh.) If this isn't seasonal allergies, its RealCig Super Concentrated flavoring I got at VapingZone. It is Chinese but I'm not... repeat not... saying it has anything at all to do with being Chinese.. that's just the only descriptor I have to give. I have used multiple flavorings in the same brand (though I don't know what that is) from the same source with no problems.
Redit LOL: Hubby just reminded me that I also used about half a dozen products on my hair three days ago. My hair is mid-back long and worn loose when I sleep. These were products from back when I was smoking and haven't used in about a year... so one of those may be the culprit. Washed my hair so we'll see. I'm leavin this whole long post just as a "goes ta show ya"... may not be vaping related at all.